The present work aimed to validate the Italian version of the Morningness-Eveningness Questionnaire for Adolescents (MEQ-A) using circadian motor activity as external criterion. A sample of 60 healthy high school students (32 boys and 28 girls) wore an actigraph (Actiwatch®) on the non-dominant wrist for seven consecutive nights and days. After the recording session, all the subjects were administered the Italian version of the MEQ-A. Results showed a significantly different circadian pattern of motor activity between morning and evening types as expected. It has been underlined that such differences were found only during week-end, when the school schedule was stop and students were free to behave according to their own rhythms. Qn the whole the results show that the MEQ-A has good external validity.